This invention relates generally to thermal protective device for lighting fixtures and more particularly to such devices for use with recessed lighting fixtures.
It has been recognized in the lighting industry that lighting fixtures mountable on ceiling or wall surfaces, especially those designed to be recessed in such surfaces, may become fire hazards under certain circumstances. Fires have been known to occur when too large wattage lamps are used in the lighting fixtures and/or where insulation surrounding the fixture prevents heat produced thereby from properly dissipating.
One attempt to overcome the aforementioned difficulties has been made by including in each lamp socket of a lighting fixture, a thermal protector which interrupts current to the socket when the socket is heated to a predetermined temperature, see U.S. Pat. No. 4,131,868, entitled incandescent Lamp Socket Having Over-Temperature Protector, issued Dec. 26, 1978.
While the thermally protected socket described in the aforementioned patent attempts to address the problems discussed heretofore, the socket arrangement is not sufficiently versatile for use with recessed lighting fixtures which can accommodate various types of trim rings, and/or reflectors and refractors which can alter the heat dissipation of the lighting fixture. Also, the placement of the thermal protector in the lamp socket can cause unnecessary cycling of the lamp between on and off conditions when in fact the actual temperature of the area surrounding the fixture is well below that which is deemed a fire hazard. Furthermore, the thermal protector included as a part of the socket can easily be circumvented, thereby rendering the protection it is intended to provide, ineffective.
The need for thermal protective devices in lighting fixtures, especially those which are to be recessed in ceiling or wall surfaces, has been recognized by certain organizations concerned with safety, such as, for example, Underwriter's Laboratory and the National Fire Prevention Association. It is believed that devices which can be rendered ineffective easily will not, however, be acceptable to such organizations.